/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
"use strict";

class Hook {
	constructor(args) {
		if(!Array.isArray(args)) args = [];
		this._args = args;
		this.taps = [];
		this.interceptors = [];
		this.call = this._call = this._createCompileDelegate("call", "sync");
		this.promise = this._promise = this._createCompileDelegate("promise", "promise");
		this.callAsync = this._callAsync = this._createCompileDelegate("callAsync", "async");
		this._x = undefined;
	}

	compile(options) {
		throw new Error("Abstract: should be overriden");
	}

	_createCall(type) {
		return this.compile({
			taps: this.taps,
			interceptors: this.interceptors,
			args: this._args,
			type: type
		});
	}

	_createCompileDelegate(name, type) {
		const lazyCompileHook = (...args) => {
			this[name] = this._createCall(type);
			console.log(this[name].toString());
			return this[name](...args);
		};
		return lazyCompileHook;
	}

	tap(options, fn) {
		if(typeof options === "string")
			options = { name: options };
		if(typeof options !== "object" || options === null)
			throw new Error("Invalid arguments to tap(options: Object, fn: function)");
		options = Object.assign({ type: "sync", fn: fn }, options);
		if(typeof options.name !== "string" || options.name === "")
			throw new Error("Missing name for tap");
		options = this._runRegisterInterceptors(options);
		this._insert(options);
	}

	tapAsync(options, fn) {
		if(typeof options === "string")
			options = { name: options };
		if(typeof options !== "object" || options === null)
			throw new Error("Invalid arguments to tapAsync(options: Object, fn: function)");
		options = Object.assign({ type: "async", fn: fn }, options);
		if(typeof options.name !== "string" || options.name === "")
			throw new Error("Missing name for tapAsync");
		options = this._runRegisterInterceptors(options);
		this._insert(options);
	}

	tapPromise(options, fn) {
		if(typeof options === "string")
			options = { name: options };
		if(typeof options !== "object" || options === null)
			throw new Error("Invalid arguments to tapPromise(options: Object, fn: function)");
		options = Object.assign({ type: "promise", fn: fn }, options);
		if(typeof options.name !== "string" || options.name === "")
			throw new Error("Missing name for tapPromise");
		options = this._runRegisterInterceptors(options);
		this._insert(options);
	}

	_runRegisterInterceptors(options) {
		for(const interceptor of this.interceptors) {
			if(interceptor.register) {
				const newOptions = interceptor.register(options);
				if(newOptions !== undefined)
					options = newOptions;
			}
		}
		return options;
	}

	withOptions(options) {
		const mergeOptions = opt => Object.assign({}, options, typeof opt === "string" ? { name: opt } : opt);

		// Prevent creating endless prototype chains
		options = Object.assign({}, options, this._withOptions);
		const base = this._withOptionsBase || this;
		const newHook = Object.create(base);

		newHook.tapAsync = (opt, fn) => base.tapAsync(mergeOptions(opt), fn),
		newHook.tap = (opt, fn) => base.tap(mergeOptions(opt), fn);
		newHook.tapPromise = (opt, fn) => base.tapPromise(mergeOptions(opt), fn);
		newHook._withOptions = options;
		newHook._withOptionsBase = base;
		return newHook;
	}

	isUsed() {
		return this.taps.length > 0 || this.interceptors.length > 0;
	}

	intercept(interceptor) {
		this._resetCompilation();
		this.interceptors.push(Object.assign({}, interceptor));
		if(interceptor.register) {
			for(let i = 0; i < this.taps.length; i++)
				this.taps[i] = interceptor.register(this.taps[i]);
		}
	}

	_resetCompilation() {
		this.call = this._call;
		this.callAsync = this._callAsync;
		this.promise = this._promise;
	}

	_insert(item) {
		this._resetCompilation();
		let before;
		if(typeof item.before === "string")
			before = new Set([item.before]);
		else if(Array.isArray(item.before)) {
			before = new Set(item.before);
		}
		let stage = 0;
		if(typeof item.stage === "number")
			stage = item.stage;
		let i = this.taps.length;
		while(i > 0) {
			i--;
			const x = this.taps[i];// 最后一个
			this.taps[i+1] = x; // 最后一个赋值为下一个
			const xStage = x.stage || 0;
			if(before) {
				if(before.has(x.name)) {// 如果before里面有这个tap
					before.delete(x.name);
					continue;
				}
				if(before.size > 0) {
					continue;
				}
			}
			if(xStage > stage) {
				continue;
			}
			i++;
			break;
		}
		this.taps[i] = item;
	}
}

module.exports = Hook;
